This invention relates generally to optocoupler devices and more particularly, to a method of manufacturing such devices wherein an emitter detector combination may be tested prior to mounting on a lead frame and encapsulation.
There are various commercially available optocoupler devices which basically comprise a semiconductor detector and a semiconductor emitter separated by a transparent dielectric material to provide electrical insulation between the detector and emitter. Most currently available devices are manufactured in such a manner that the emitter and detector portions of the device are separately and individually mounted to a lead frame and tested separately prior to their combination into a single optocoupler device. In addition to various testing steps, most current methods of manufacture require a relatively critical alignment between the two separate lead frames with attached emitter and detector elements during the final stages of construction. In addition, there is normally not a test of the emitter detector combination until the entire device has been attached to the lead frame and in some cases after encapsulation. While some prior art devices do provide for the direct attachment of the emitter device to a dielectric material which has been applied to the detector device and therefore a relatively tight control of the coupling between the two devices, even this method requires the separate attachment of the emitter and detector circuits to a separate lead frame prior to any testing of the combination.
It would therefore be desirable to provide a method of assembling an optocoupler device which would reduce or eliminate critical lead frame alignments, elimiate multiple plastic molds, improve optical coupling, and allow testing of a die pair comprising an emitter and a detector prior to mounting on a lead frame or encapsulation.